Add implementation of pthread_rwlock based on NaCl futexs

src/untrusted/pthread/nacl.scons

 # -*- python -*-
 # Copyright (c) 2012 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 Import('env')
 
 # (elijahtaylor): Removing so braced groups will work for GC syscall wrapping.
 env.FilterOut(CCFLAGS=['-pedantic'])
 
@@ skipping 17 matching lines @@
 valgrind = env.ComponentObject(
     'valgrind_annotations.o',
     '${MAIN_DIR}/src/untrusted/valgrind/dynamic_annotations.c')
 
 nc_objs = [env.ComponentObject(module, module + '.c')
            for module in [
                'nc_thread',
                'nc_mutex',
                'nc_condvar',
                'nc_semaphore',
+               'nc_rwlock',
                'stack_end',
                ]
            ] + [valgrind]
 
 # The public library relies on the IRT for crucial system services.
 libpthread = env.ComponentLibrary('libpthread', nc_objs + ['nc_init_irt.c'])
 env.AddLibraryToSdk(libpthread)
 
 if env.Bit('nonsfi_nacl'):
   nc_private_objs = nc_objs + [
@@ skipping 27 matching lines @@
   # installed, we ensure that they are in place before they're used.
   for compiler in ['${CC}', '${CXX}']:
     # TODO(mcgrathr): This can't be the best way!  Ideally we'd just use
     # '${CC}' directly in env.Depends and that should be fine for scons.
     # But sometimes '${CC}' is not just '.../gcc', it's '.../gcc -m32'.
     compiler = env.subst(compiler).split()[0]
     env.Depends(env.WhereIs(compiler), n)
 else:
   n = []
 env.Alias('install_libpthread', n)